st1100 fuel gauge fault

Hi all just bought this bike yesterday and not had chance to get a repair manual as of yet and the fuel gauge is showing a full tank but there,s maybe a couple of gallon in at most,probably needs the sender cleaning but i would,nt know were to look for it, any info would be great,also what sort of mileage would be expected from a tank of gas 2 up with luggage,thanks

The range for this bike is between 400km-500km (250miles-300miles) the gauge will indicate full for close to 150km or 100 miles then drop fast. The sender is located in the lower part of the tank. So the float stays up till the first couple of gallons are consumed. The tank holds 28 litres of fuel

kiltman said:

The range for this bike is between 400km-500km (250miles-300miles) the gauge will indicate full for close to 150km or 100 miles then drop fast. The sender is located in the lower part of the tank. So the float stays up till the first couple of gallons are consumed. The tank holds 28 litres of fuel

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Thanks mate for the swift reply

My 1991 reads max until after 120 miles or so. The indicator will not drop when you turn the bike off, fyi. If you need to service the sending unit, it is mounted to the left side of the tank, low down. You would need to drain/remove the tank....not difficult, just a little time consuming. Don't reuse the old seal.

Be careful to disconnect the sending unit connector before you remove the tank. It's on the left side of the tank.

Oldbikefixr said:

My 1991 reads max until after 120 miles or so. The indicator will not drop when you turn the bike off, fyi. If you need to service the sending unit, it is mounted to the left side of the tank, low down. You would need to drain/remove the tank....not difficult, just a little time consuming. Don't reuse the old seal.

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Thanks mate for that info,just been and pushed the float down with a long screwdriver and lo and behold the gauge dropped

Jim Van said:

Be careful to disconnect the sending unit connector before you remove the tank. It's on the left side of the tank.

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sorted jim thanks

Jim Van said:

Be careful to disconnect the sending unit connector before you remove the tank. It's on the left side of the tank.

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I had to remove the fuel tank when I repaired a coolant leak at the rear of the engine and everything worked fine afterwards but a few weeks later the fuel gauge started to play up ———-like dropping to empty and then slowly creeping back up to show there was fuel in the tank but has now stopped working completely.
I am at this moment trying to remove the gauge cluster as I suspected the gauge and it REALLY is a godawful job but then started to think it could be elsewhere——-is there any way of finding out where the fault lies?
I would be ticked off if I replace the gauge only to find the fault is in the fuel tank.
Is it the side sensor that shows the amount of fuel in the tank or the top one?
Thanks.

Graham Watson

Graham Watson said:

Is it the side sensor that shows the amount of fuel in the tank

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Yes.

This is one case where the Clymer manual is better than the Honda Service Manual, as it describes the test for that sending unit. Page 269, if you have one.

Couple of phone pics of the pages. The Table 3 referred to says Fuel unit resistance at full level is 10 ohms - at empty should read 90 ohms. Hope that helps.

Bush said:

This is one case where the Clymer manual is better than the Honda Service Manual, as it describes the test for that sending unit. Page 269, if you have one.

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Bush,
Thanks very much for the info.
As I don’t know my Ohms from my Amps, I’ll go and see my Electrician Wizard and let him sort it for me using the info you sent.
Again, thanks very much for your help.
Regards,
Graham Watson